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The effect of the equatorially symmetric zonal winds of Saturn on its gravitational field

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Research in Astronomy and Astrophysics 2018年第4期18卷 15-22页

作者： dali Kong Keke Zhang Gerald Schubert john d.Anderson Key Laboratory of Planetary Sciences Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030 China College of Engineering Mathematics and Physical Sciences University of Exeter Exeter EX4 4QF UK Lunar and Planetary Science Laboratory Macao University of Science and Technology Macao China department of Earth Planetary and Space Sciences University of California Los Angeles CA 90095-1567 USA Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena CA 91109 USA

The penetration depth of Saturn’s cloud-level winds into its interior is unknown.A possible way of estimating the depth is through measurement of the effect of the winds on the planet’s gravitational *** use a self-consistent perturbation approach to study how the equatorially symmetric zonal winds of Saturn contribute to its gravitational *** important advantage of this approach is that the variation of its gravitational field solely caused by the winds can be isolated and identified because the leading-order problem accounts exactly for rotational distortion,thereby determining the irregular shape and internal structure of the hydrostatic *** assume that（i）the zonal winds are maintained by thermal convection in the form of non-axisymmetric columnar rolls and（ii）the internal structure of the winds,because of the Taylor-Proundman theorem,can be uniquely determined by the observed cloud-level *** calculate both the variation △J_n,n=2,4,6...of the axisymmetric gravitational coefficients J_n caused by the zonal winds and the non-axisymmetric gravitational coefficients △J_（nm） produced by the columnar rolls,where m is the azimuthal wavenumber of the *** consider three different cases characterized by the penetration depth 0.36 R_S,0.2 R_S and 0.1 R_S,where R_S is the equatorial radius of Saturn at the 1-bar pressure *** find that the high-degree gravitational coefficient （ J_（12）＋△J_（12）） is dominated,in all the three cases,by the effect of the zonal flow with ｜△J_（12）/J_（12）｜〉100%and that the size of the non-axisymmetric coefficientsdirectly reflects the depth and scale of the flow taking place in the Saturnian interior.

关键词： gravitation — planets and satellites individual(Saturn) — planets and satellites interiors

Saturn＇s gravitational field induced by its equatorially antisymmetric zonal winds

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Research in Astronomy and Astrophysics 2018年第5期18卷 29-36页

作者： dali Kong Keke Zhang Gerald Schubert john d.Anderson Key Laboratory of Planetary Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China College of Engineering Mathematics and Physical Sciences University of Exeter Exeter EX4 4QF UK Lunar and Planetary Science Laboratory Macao University of Science and Technology Macao China department of Earth Planetary and Space Sciences University of California Los Angeles CA 90095-1567 USA Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena CA 91109 USA

The cloud-level zonal winds of Saturn are marked by a substantial equatorially antisymmetric component with a speed of about 50 m s^-1 which, if they are sufficiently deep, can produce measurable odd zonal gravitational coefficients △J2 k＋1, k = 1, 2, 3, 4. This study, based on solutions of the thermal-gravitational wind equation, provides a theoretical basis for interpreting the odd gravitational coefficients of Saturn in terms of its equatorially antisymmetric zonal flow. We adopt a Saturnian model comprising an ice-rock core, a metallic dynamo region and an outer molecular envelope. We use an equatorially antisymmetric zonal flow that is parameterized, confined in the molecular envelope and satisfies the solvability condition required for the thermal-gravitational wind equation. The structure and amplitude of the zonal flow at the cloud level are chosen to be consistent with observations of *** calculate the odd zonal gravitational coefficients △J2k＋1, k = 1, 2, 3, 4 by regarding the depth of the equatorially antisymmetric winds as a parameter. It is found that △J3 is-4.197 × 10^-8 if the zonal winds extend about 13 000 km downward from the cloud tops while it is-0.765 × 10^-8 if the depth is about 4000 km. The depth/profile of the equatorially antisymmetric zonal winds can eventually be estimated when the high-precision measurements of the Cassini Grand Finale become available.

关键词： gravitation - planets and satellites individual (Saturn) - planets and satellites interiors

Investigation of active vibration drilling using acoustic emission and cutting size analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 390-401页

作者： Yingjian Xiao Charles Hurich john Molgaard Stephen d.Butt Faculty of Engineering and Applied Science Memorial University of Newfoundland department of Earth Sciences Memorial University of Newfoundland

This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit. A series of drill-off tests(dOTs) were conducted where the drilling rate-of-penetration(ROP) was measured at a series of step-wise increasing static bit thrusts or weight-on-bits(WOBs). Two active dOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples, and a passive dOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings. during drilling, an acoustic emission(AE) system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis. The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor, a load cell, and an LVdT(linear variable differential transformer) recorded the dynamic WOB and the ROP, respectively. Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB, facilitating comparison of the results at the same WOB. Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration, and the drill cuttings increased in size with a higher ROP. Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency. This indicated that larger fractures were being created to generate larger cutting size. Overall, these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which, at the same rotary speed, results in a higher ROP.

关键词： Active bit vibration diamond coring drilling drill-off tests(dOTs) Acoustic emission(AE) drilling performance Penetration mechanism Cutting size analysis

A model of Saturn inferred from its measured gravitational field

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Research in Astronomy and Astrophysics 2018年第4期18卷 7-14页

作者： dali Kong Keke Zhang Gerald Schubert john d.Anderson Key Laboratory of Planetary Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China College of Engineering Mathematics and Physical Sciences University of Exeter Exeter EX4 4QF UK Lunar and Planetary Science Laboratory Macao University of Science and Technology Macao China department of Earth Planetary and Space Sciences University of California Los Angeles CA 90095-1567 USA Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena CA 91109 USA

We present an interior model of Saturn with an ice-rock core,a metallic region,an outer molecular envelope and a thin transition layer between the metallic and molecular *** shape of Saturn’s 1 bar surface is irregular and determined fully self-consistently by the required equilibrium *** the ice-rock core is assumed to have a uniform density,three different equations of state are adopted for the metallic,molecular and transition *** Saturnian model is constrained by its known mass,its known equatorial and polar radii,and its known zonal gravitational coefficients,J_（2n）,n=1,2,*** model produces an ice-rock core with equatorial radius 0.203 R_S,where R_S is the equatorial radius of Saturn at the 1-bar pressure surface;the core densityρ_c=10388.1 kgm^（3）corresponding to 13.06 Earth masses;and an analytical expression describing the Saturnian irregular shape of the 1-bar pressure *** model also predicts the values of the higher-order gravitational coefficients,J_8,J_10 and J_12,for the hydrostatic Saturn and suggests that Saturn’s convective dynamo operates in the metallic region approximately defined by 0.2 R_S

关键词： gravitation — planets and satellites individual(Saturn) — planets and satellites interiors

Evolution-aided engineering of plant specialized metabolism

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aBIOTECH 2021年第3期2卷 240-263页

作者： Mohammad Irfan Benjamin Chavez Paride Rizzo john C.d'Auria Gaurav d.Moghe Plant Biology Section School of Integrative Plant ScienceCornell UniversityIthacaNYUSA Metabolic diversity Group Leibniz Institute of Plant Genetics and Crop Plant Research(IPK)06466 SeelandGermany

The evolution of new traits in living organisms occurs via the processes of mutation,recombination,genetic drift,and *** processes that have resulted in the immense biol ogical diversity on our planet are also being employed in metabolic engineering to optimize enzymes and pathways,create new-to-nature reactions,and synthesize complex natural products in heterologous *** this review,we discuss two evolution-aided strategies for metabolic engineering-directed evolution,which improves upon existing genetic templates using the evolutionary process,and combinatorial pathway reconstruction,which brings together genes evolved in different organisms into a single heterol ogous *** discuss the general principles of these strategies,describe the technologies involved and the molecular traits they influence,provide examples of their use,and discuss the roadblocks that need to be addressed for their wider adoption.A better understanding of these strategies can provide an impetus to research on gene function discovery and biochemical evolution,which is foundational for improved metabolic *** evolution-aided approaches thus have a substantial potential for improving our understanding of plant metabolism in general,for enhancing the production of plant metabolites,and in sustainable agriculture.

关键词： Evolution Metabolic engineering Plant biotechnology Synthetic biology

Structural health monitoring of bridges in the State of Connecticut

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Earthquake Engineering and Engineering Vibration 2008年第4期7卷 427-437页

作者： Chengyin Liu Joshua Olund Alan Cardini Paul d＇Attilio Eric Feldblum john deWolf SP-SELLS Inc. Briarcliff Manor NY 10510 USA department of Civil and Environmental Engineering University of Connecticut 261 Glenbrook Rd Unit 2037 Storrs CT06269 USA dMJM Harris Boston MA 02110 USA Connecticut department of Transportation 280 West Street Rocky Hill CT 06067 USA

A joint effort between the Connecticut department of Transportation and the University of Connecticut has been underway for more than 20 years to utilize various structural monitoring approaches to assess different bridges in Connecticut. This has been done to determine the performance of existing bridges, refine techniques needed to evaluate different bridge components, and develop approaches that can be used to provide a continuous status of a bridge＇s structural integrity. This paper briefly introduces the background of these studies, with emphasis on recent research and the development of structural health monitoring concepts. This paper presents the results from three different bridge types： a post-tensioned curved concrete box girder bridge, a curved steel box-girder bridge, and a steel multi-girder bridge. The structural health monitoring approaches to be discussed have been successfully tested using field data collected during multi-year monitoring periods, and are based on vibrations, rotations and strains. The goal has been to develop cost-effective strategies to provide critical information needed to manage the State of Connecticut＇s bridge infrastructure.

关键词： structural integrity structural health monitoring field data vibrations

Quantifying spatiotemporal variability in occupant exposure to an indoor airborne contaminant with an uncertain source location

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Building Simulation 2023年第6期16卷 889-913页

作者： john E.Castellini Jr Cary A.Faulkner Wangda Zuo Michael d.Sohn department of Mechanical Engineering University of Colorado BoulderUCB 427BoulderCO80309USA department Architectural Engineering The Pennsylvania State UniversityUniversity ParkPA16802USA National Renewable Energy National Laboratory GoldenCO80401USA Energy Analysis and Environmental Impacts division Lawrence Berkeley National Laboratory1 Cyclotron RoadBerkeleyCA94720USA

Well-mixed zone models are often employed to compute indoor air quality and occupant *** effective,a potential downside to assuming instantaneous,perfect mixing is underpredicting exposures to high intermittent concentrations within a *** such cases are of concern,more spatially resolved models,like computational-fluid dynamics methods,are used for some or all of the ***,these models have higher computational costs and require more input information.A preferred compromise would be to continue with a multi-zone modeling approach for all rooms,but with a better assessment of the spatial variability within a *** do so,we present a quantitative method for estimating a room’s spatiotemporal variability,based on influential room *** proposed method disaggregates variability into the variability in a room’s average concentration,and the spatial variability within the room relative to that *** enables a detailed assessment of how variability in particular room parameters impacts the uncertain occupant *** demonstrate the utility of this method,we simulate contaminant dispersion for a variety of possible source *** compute breathing-zone exposure during the releasing(source is active)and decaying(source is removed)*** CFd methods,we found after a 30 minutes release the average standard deviation in the spatial distribution of exposure was approximately 28%of the source average exposure,whereas variability in the different average exposures was lower,only 10%of the total *** also find that although uncertainty in the source location leads to variability in the average magnitude of transient exposure,it does not have a particularly large influence on the spatial distribution during the decaying period,or on the average contaminant removal *** systematically characterizing a room’s average concentration,its variability,and the spatial variability within the room important insights can be gain

关键词： uncertainty variability airborne contaminant spatiotemporal variability well-mixed heterogeneity

Regression of recurrent granulosa cell tumor liver metastases following selective internal radiation therapy

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Hepatobiliary & Pancreatic diseases International 2023年第4期22卷 406-408页

作者： Omar A Mownah john d Leahy Jeffrey Summers Stephen M Gregory Nigel d Heaton Institute of Liver Studies King’s Healthcare PartnersKing’s College Hospital NHS Foundation TrustDenmark HillLondon SE59RSUK department of Oncology Maidstone and Tunbridge Wells NHS TrustMaidstone ME169QQUK

Granulosa cell tumor(GCT)is the most common sex cordstromal tumor,comprising 5%of all ovarian malignancies[1].The disease course is indolent,and the majority of cases present at stage ***,metastases may develop with potential sites being peritoneum,lung,brain,liver and bone[2].due to the rarity of the disease,published evidence for management of granulosa cell tumor liver metastases(GCTLM)is *** resection is the optimal treatment in instances where there is a high chance of achieving complete resection[3].With regards to unresectable GCTLM there is a paucity of evidence to guide treatment strategy.

关键词： metastases liver lung

Flexible ureteroscopy:Technological advancements,current indications and outcomes in the treatment of urolithiasis

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Asian Journal of Urology 2015年第3期2卷 133-141页

作者： Husain Alenezi john d.denstedt division of Urology Department of SurgerySchulich School of Medicine&DentistryWestern UniversityLondonOntarioCanada

The last 3 decades have witnessed great improvements in the technology and clinical applications of many minimally invasive procedures in the urological *** ureteroscopy(fURS)has advanced considerably to become a widely utilized diagnostic and therapeutic tool for multiple upper urinary tract *** most common indication for fURS is the treatment of upper urinary tract stones with the aid of Holmium:Yttrium Aluminium Garnet(YAG)laser *** in endoscope technologies and operative techniques have lead to a broader application of fURS in the management of urolithiasis to include larger and more complex *** has proved to be an effective and safe procedure with few *** progression in fURS may increase its clinical applicability and supplant other procedures as the first line treatment option for urolithiasis.

关键词： Flexible ureteroscopy Urolithiasis Renal stone Endoscopy